Overload protective device



Sept. 942. F. J. RUSSELL 2,295,691

OVERLOAD PROTECTIVE DEVICE Filed June 24, 1941 Patented Sept. 15, 1942 I r t I w UNITED STATES PATENT OFFICE OVERLOAD' PROTECTIVE DEVICE Frank J. Russell, Wauwatosa, Wis., assignor to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware I v Application June 24, 1941, Serial No. 399,558

Claims. (01. 200-97) This invention relates to overload protective The relay shown is also provided with a shunt devices, and more particularly to electroresponholding coil II, the purpose of which is to mainsive overload relays of the dash pot type. tain the relay in tripped position after the same The invention has among its objects to prohas operated. vide an improved dash pot for use in connection 5 In accordance with the present invention plungwith an overload relay which provides for reer 6 is loosely supported within a tubular sleeve tarded response of the relay to overloads up to 12 which is externally threaded to fit within a a predetermined value and substantially instantapped opening in the lower leg of magnet frame taneous response to overloads in excess of such 1. The lower end of sleeve [2 is closed by a cupvalue. shaped dash pot l3 which contains a piston [4.

Another object is to provide a dash pot of the The inner diameter of dash pot I4 is less than aforesaid character having an improved valve that of sleeve [2 and as shown in Fig. 2 piston [A mechanism associated therewith which is simis operatively connected to the lower end of ple and rugged in construction, and positive and plunger 6 and is provided with a valve mechareliable in operation. v hism including valve disks l5 and I6.

Various other objects and advantages of the I More specifically piston M has its under side invention will hereinafter appear. recessed to provide a top wall I! and a de- The accompanying drawing illustrates an empending skirt l8. Skirt I8 is provided with oppoleodiment of the invention which will now be desitely disposed openings l9--l9 and the top wall scribed, it being understood that the embodi- I1 is provided with a center opening for receivment illustrated is susceptible of modification ing a centrally located stem projection 20 on the without departing from the spirit and scope under side of valve disk I5. Piston I4 is biased cf the appended claims. to move toward valve disk [5 by a spring 2| In the drawing, which is held under compression between the Figure 1 is a side view partly in section of an 2.5 top wall ll of said piston and a headed screw 22 overload relay embodying the invention; which is adjustable within a tapped opening in Fig. 2 is an enlarged sectional view of a dash stem projection 20. Valve disk is is provided pot piston employed in the dash pot shown in with a center opening for receiving a centrally Fig. l, and located stem projection 23 on the upper side of Fig. 3 is a sectional view on line 3-3 of Fig. 2. valve disk l5. The uppe end of m P j Referring to Fig. 1, the same illustrates an tion 23 is attached to an extension 24 of reoverload relay of a well known type having a duced diameter on the lower end of plunger dash pot embodying the invention associated 6 by a pin 25. therewith. Briefly described the relay shown in- The top face of piston wall I! is provided eludes apivoted contact element I which is biased 5 with a circular recess 26 and said wall is also by a spring 2 to bridge a pair of stationary conprovided with a plurality of ports 21 which are tacts mounted upon an insulating panel 3. One located within said recess. The upper face of of the stationary contacts is illustrated at 4 in valve disk [5 is provided with a circular recess Fig, 1, and contact element 1 is movable out 28 and the lower face thereof iS provided with of engagement with said stationary contacts by 4 a circular recess 29, and said valve disk has a a solenoid operating mechanism including an plurality of ports 30 which are located within overload coil 5 and a plunger 6. Coil 5 is carsaid recesses. A thin gasket 3| of annular form ried by a C-shaped magnet frame 1 mounted having openings 32 therein is associated with the upon insulating panel 3, and plunger 6 is norunder side of valve disk l5 and a thin gasket mally held by gravity in the position shown and washer 33 of annular form is associated with is attracted upwardly out of normal position into the under side of valve disk l6.

engagement with a magnetic plug 8 mounted The function and operation of the aforedeupon the upper leg of said magnet frame when scribed dash pot mechanism is as follows. Dash the current in said coil exceeds a predetermined pot l3 and the lower end of sleeve l2 contain a overload value. Plunger 6 has a pin extension fluid such as oil, and piston I4 is normally held 5-) on the upper end thereof and during final against the bottom of said dash pot by the movement of said plunger into its attracted poweight of plunger 6. The gasket 33 associated sition said pin engages an arm in associated with wi h v lv i k I6 s normally se ed against contact element l to move said contact element the upper face of valve disk 15 and the gasket out of engagement with stationary contacts 4. 3| associated with valve disk I5 is normally seated against the upper face of piston l4 under the action of spring 2|. The ports 21 in piston H are therefore normally closed to prevent passage of the dash pot fluid therethrough upon upward movement of said piston within dash pot 53. Assuming that plunger 6 responds to a moderate overload current condition in coil 5, spring 2! acts to maintain piston M in seating engagement with gasket 3| and upward movement of said plunger is thus retarded by'a slow passage of the dash pot fluid around the outer surface of said piston. Prior to full movement of plunger 6 into its attracted position the openings 19 in the piston skirt [4 are moved out of the core in dash pct 13 and the dash pot fluid is then permitted to pass rapidly through said openings to provide for opening of c'onta'ctelement I by quick movement its attracted position,

Assuming that plunger 6 is moved out of nor mal position in response to a heavy overload current condition in coil 5, spring 2! is adaptedto yield'against theretarding'action of dash" pot I 4 to permitupward movement of valve disk"! 5 with respect to piston I4; Thepistonports' 21 are thus opened to permit free passage of the dash pot fluid therethrough for substantially instantaneous response of plunger 6. Y j I I From the foregoing it is' apparent that the above described dash pot mechanismprovides fonretarded response of the relay to overloads 'up to a predetermined value which is determined by the degree of compression of spring 2 and for substantially instantaneous response of the relay to overloads m excess' of such value. I I

Upon downward movementiof piston l4 valve disk l5 anditsassociated gasketwasher 3 3 are lifted to permit free passage of the dash pot fluid from the under side of piston 'l 4 through the ports 2?. in said pistorr'and the portsjqjn valve disk 15. Provision is thus made for permitting quick returnof plunger 6 to normalposition dur of plunger 6 into ing resetting of the relays V I A,

What I claim as new and desire to secure by Letters Patent is:

1. In a circuit breaker; in combination, a switch, an overload tripping solenoid therefor, and a dash pot'mechanism associated with said solenoid including a fluid containing dash pot, a

piston movable Within said dash pot and; having a spring operating connection between the same and said operating solenoid, and a valve mechanism associated with said piston and controlled by said spring operating connection to provide for delayed response of said solenoid under overload conditions below a predetermined value, and for substantially instantaneous response of said solenoid under overload conditions in excess of said valuej 2. In a circuit breaker, in combination, a switch, an overload responsive tripping solenoid therefor, and-a dash pot mechanism associated with said solenoid including a fluid containing dash pot, a piston movable within said dash pot, a valve member associated with said piston and movable by said tripping solenoid upon response thereof and a springfor normally maintaining said piston in engagement with said valve memher to provide for delayed response of said solenoid under overload conditions below a predetermined value, said spring permitting disengagement of said piston and valve member for substantially instantaneous response of said solenoid under overload conditions in excess of said predetermined value.

3. In a circuit breaker, in combination, a switch, an overload responsive tripping solenoid therefor, and a dash pot mechanism associated with said solenoid including a fluid containing dash pot, a piston movable within said dash pot. a valve member associated with said piston and movable by said tripping solenoid upon response thereof, a spring for normally maintaining said piston in engagement with said valve member to provide for dela'yed'response of said solenoid underove'rl'oad conditions below a predetermined value, said spring permitting disengagement of said piston and valve member for substantially instantaneous response of said solenoid under overload conditions in excess of said predetermined value, and a second valve member associated with said former valve member for per mitting quick resetting movement of said trip ping solenoid. V

a circuit breaker, in combination, a switch, an electromagnetic overload responsive tripping device therefor, and a dash pot mechanism associated with said device including a cup shaped fluid containing dash pot, a piston movable upwardly within said dash pot upon response of said device, said piston having ports therein for passage of the dash pot fluid therethrough, a valve mechanism movable by said tripping device and associated with the upper surface of said piston to effect closure of said ports, a spring for normally maintainingsaid piston in engagement with said valve mechanism to provide for closure of said ports upon response of said device to overload conditions belowja, predetermined value said spring permitting disengagement of saidpiston from said valve mechanism for opening of said ports upon response ,of said device to overload conditions in excess of said predetermined value.

5. In a circuit breaker, in combination, a switch, an electromagnetic overload responsive tripping device therefor, a dash pot mechanism associated with said device including acupshaped fluid containing dash pot, a piston movable upwardly within said dash pot upon rcspcnseof said device, said piston having ports therein for passage of the dash pot fluid therethrough, a valve member movable by said tripping device and associated with 'the upper surface of'said pistonto effect closure of said ports, a spring normally maintaining said piston in engagement with said valve member to provide for closure ,of said ports upon response of said device to'overload conditions below a predetermined value, said spring permitting disengagement of said piston from said valve member for opening of said ports uponresponse of said device to overload conditions in excess of said predetermined value, and a second valve member associated with said former valve member for effecting opening of said piston ports, during return movement of said tripping device to normal position.

j, FRANK J. RUSSELL. 

